Recent Development on Fullerene Chemistry Part 1: Cycloaddition of o-Quinodimethane and Its Analogs to [60] Fullerene, and Properties of Cycloadducts

Several C60-o-quinodimethane adducts having various aromatic rings have been synthesized by the simple thermal reaction of C60 with benzocyclobutene homologues. The electronic and photophysical properties of the adducts were found to be virtually independent of the attached aromatic rings, according to the absorption, fluorescence, and transient absorption spectra. In the adduct possessing an N, N-dimethylaniline (DMA) moiety, however, intramolecular electron transfer from S0 (DMA) to S1 (C60) was observed in benzonitrile, while not in cyclohexane. The regio- and stereoselective synthesis of C60-bisadducts has been successful by the reaction between C60 and the compounds in which two o-quinodimethane precursors were connected by an oligomethylene unit of the suitable length (n=2-5). A new nomenclature of C60 derivatives is also proposed in order to designate such bisadducts.